ABSTRACTRecent studies have demonstrated that microRNAs regulate gene expression and are related to cancer progression. Increasing evidence shows that miR‐618 plays an important role in a variety of tumors, including thyroid carcinomas, breast cancer and lymphoma cancer. However, no studies have examined the expression or function of miR‐618 in gastric cancer (GC). In this study, we examined the effects and molecular mechanisms of miR‐618 in GC. We compared the expression levels of miR‐618 in 90 paired GC tissues and adjacent noncancerous tissues. Cell cycle, apoptosis and transwell assays were performed in GC cells with miR‐618 mimic or inhibitor in vitro. We first used quantitative PCR(qPCR) to show that miR‐618 expression levels were downregulated in GC tissues, which showed statistical significance. Next we used transwell assays to prove that miR‐618 suppressed the invasion and migration capacity of GC cells. Furthermore, screening of the miRDB and Target Scan Human databases indicated TGF‐β2 as a downstream target of miR‐618. In further research, we identified TGF‐β2 as a target gene of miR‐618 by the luciferase reporter assay. Western blot analysis confirmed that TGF‐β2 expression was inversely correlated with miR‐618 expression. In situ hybridization showed that miR‐618 expression level was downregulated in GC tissues. In conclusion, our findings suggest that miR‐618 may function as a tumor suppressor in GC and suppresses metastasis in GC by negatively regulating the transcriptional level of TGF‐β2. Anat Rec, 302:931–940, 2019. © 2019 Wiley Periodicals, Inc.